Method of seasoning cable



Dec. 17, was.

P. H. CHASE 2,024,144

METHOD OF SEASONING CABLE Filed Jan. 25, 1930 3 Sheets-Sheet 1 Dec. 17, 1935.

P. H. CHASE METHOD OF SEASONING CABLE Filed Jany 25, 1950 5 Sheets-Sheet 2 Dec. 17, 1935. p H CHASE 2,024,144

METHOD OF SEASONING CABLE y Filed Jan. 25, 1930 5 Sheets-Sheet 3 Fortement t7@ 1935 UNITED STATES oFFlcE This invention relates to cable, including the manufacture, installation and operation thereof, and more particularly to cable of the type having one or more expansion members therein.

Among the several objects oi the invention may be noted the provision of methods and means for controlling the pressure Within a cable during manufacture, test and installation thereof; tbe provision oi methods and means for heating or cooling a cable during manufacture, test and installation; the provision of methods and means for adjustment ci the fluid in cable expansion members; tlie provision of means for seasoning a cable before it is placed in operation.; and the provision of means for cooling the cable internally oi its sheath, during operation. yOt'ner ob- `:iects will be in bart obvious and in part pointed out hereinafter.

'l'.be invention accordingly comprises tbe elen'lents and combinations of elements, features of construction and operation, arrangements of parts, steps and sequence oi steps which are exernplined in the structure hereinafter described and tbe scope or application oi which will be indicated in the following claims.

lin the accompanying. drawings in which are illustrated several embodiments of the invention,

Fig. l is a cross section exemplifying the class oi cable to which the invention applies;

Fig. 2 is a fragmentary longitudinal section ilm lustrating a fluid connection between certain exlcansib-le members and a circulating system;

Fig. 3 is a view similar to Fig. 2 snowing a valved connection alternative to that shown in Fig. 2;

Fig. 4lsliows a reel ci cable connected with a i'luid circulating system;

Fig. 5 is a side elevation oi a reservoir, certain portions being broken away;

Fig. S is a piping diagram showing an intenconnected system including tlie expansible meinbers of a cable;

Fig. l is a view similar to Fig. 6 snowing a modification; and,

Figs. 6 to 13 are schematic illustrations of sys tenis for interconnecting cable expansible members with one another and/or reservoirs.

Similar reference characters indicate correspending parts throughout the several vier/'s of tbe drawings.

Referring now more particularly to Fig. l, there are iJu-strated at numerals conductors. The conductor insulation is illustrated by numeral 22, tile outer siieatli by numeral 3. @ne er more expansion members, or expansible hollow tubes or tapes are designated 'by numerals t. Lateral spaces designated by numerals 5 and the central space designated by numeral l, are preferablyr filled with solid filler material. The voids in the conductors, insulation and fillers are preferably 5 entirely filled with a suitable impregnating, in sulating compound or oil.

Illhe longitudinal hollow tubes @l are constructed of a suitable strong exible material, such as copper, for example, with walls impervious to the lo irnpregnating compound or oil. They may contain either a gaseous or a liquid iiuid. These enm parisien members are preferably continuous irom end to end of each cable length or may comprise a series of hollow tubes connected together so le that the fluid therein can pass serially thereG through. "llie detailed method oi, and means for connecting and filling these hollow tubes durk ing manufacture, test, installation and operation will be determined by tbe various conditions to be described herein, but it is to be understood tliat they all come Within the invention herein disclosed.

Toe hollow tubes are preferably introduced during the process of cabling the insulated con= 2li ductors together. Or, tbe hollow tubes or tapes may be incorporated in the conductor, or in the Fillers, or under the outer sheath at other anpropriate stages in the manufacture of the cable. During incorporation in tlie cable, tbe hollow so tubes may contain tbe saine or a different uuid from that to be utized during operation, and they may be introduced in a contracted siriane, suoli as with the side tube Walls touching or practically touching, or in a relatively expanded shape. It will be understood that other shapes not corresponding to the original one in Wln'cli tbe loollow tubes are manufactured may be ei- 'footed by increasing or decreasing tbe internal pressure within said hollow tubes. The tubes in 40 any event will terminate at or adjacent the ends oi the cable length, and will be adapted, by means vof ttings soldered or clamped to the tube ends,

for closing or for connecting pressure or fluid introducing means.

For instance, Fig. 2 illustrates a fitting il which is adapted to connect the tube il to a nine l@ through which connections are made to pumps, oil and gas containers, gauges the lilre. @ne end of the fitting or nipple il is preferably soldared to the tubing l and the other end is thread ed for tbe reception or a .iarnb nut or cap to retain tbe end o" tbe Fig. :E illustrates al tive term oi litting ntted with a tapered member lo to serve as a shut-oil valve, open when the hole Lil registers with the passage 9, and closed when the cock is turned 90 from the open position.

Thus after the hollow tube or tubes have been introduced into or applied to the cable core, pressure or vacuum may be applied to them through the fittings of Figs. 2 and 3 at one or both ends, for example by means of a pump, in order to detect faults or leaks through the tube walls and, if desired, to expand or contract the tubes to a predetermined area. o! cross section. For example, Fig. 4 illustrates a reel or support Il for manufacture and/or transportation of cable; in which the reel iianges are designated by numeral IS, the cable ends by numeral I1, and the hollow tube or tubes by numeral 4, connected to a control system. For a test for tube leakage, valves 2G and 21 are closed and valve 23 is opened. The valves 26 and 21 are in circulating pipes I0 (now cut o) in the lower branch of which is located a pump 22 and in the upper branch a suction or pressure pipe 3|!V (including valve 23) which passes to a vacuum or pressure pump P. Whether the pump P exerts a vacuum or pressure depends on conditions to be described. The application of .pressure (or vacuum) to pipe 30 will exert pressure (or vacuum) through the upper pipes l0, fittings 2| and on the tube 4, throughout its length in the cable and to the now closed valve fitting 26. The valve fittings 23, 26 and 21 may be oi.' the type described in Fig. 3. By means of the pressure (or vacuum) gauge 20 the pressure on the tube I can be known and hence adjusted to the desired value, and leaks may be detected by a change in pressure as indicated on gauge 20 and/or by visual or other inspection of the cable.

During and immediately following the impregv' nating process it is preferable for the hollow tube or tubes to be similarly connected to pressure gauges and be under pressure (when the vacuum is being applied to the cable in the impregnating tank), in order to detect leaks in the hollow tubes.

The hollow tubes may also be utilized for more rapid heating or cooling of the cable, by circulating through the tubes suitable gases or liquids,

such as air or thin oil for example, heated or cooled to the desired temperature. For this purpose the system of Fig. 4 is operated with the valves 26 and 21 open and valve 23 closed, thus connecting the tubes l to a iluid containing tank T, partly or wholly iilled with iluid 3|. In the pipe line to the lower side of the tank is shown a circulating pump 22 driven by a motor, which circulates the fluid in a closed path from the tank through the valves 26, the tubes 4 in the cable, the fittings and 2|, the valve 21 and thence back to the tank. Pressure may be applied simultaneously by a pressure pump connected to pipe 3l by opening valve 23. Heating or cooling of the iluid in the tank may be effected by the addition of heat to or the removal of heat from the walls of the tank or by means of heating or cooling coils C within the tank.

During the sheathing process, the amount and/or pressure of gas or liquid in the hollow tube or tubes may be changed by the above described means, in order to bring the tube cross section to a predetermined value before or while a sheath is being applied, in order that the expansion and contraction of the tubes during operation will fall within desired limits. However, ii' it be desired to provide more fully for stretching of the outer sheath (particularly if it is lead) during manufacture and installation. or if .it iS desired to insure against voids in the cable by purposely stretching the sheath after installation, for example, the gas or liquid in the tube or tubes during the sheathing operation is removed or the quantity is reduced to allow the tube 5 cross section to become a predetermined minimum.

When the cable lengths are being tested, for example, for dielectric loss, and power factor, orl dielectric strength, the internal pressure and/or 10 temperature of the cable can, by means of this invention, be brought to and maintained at predetermined values and thus further stabilize test conditions. This is done by applying the desired pressure and/or heat to the hollow tube or tubes, 15 by the above described means.

After the application of the outer sheath, and particularly during shipment, storage and installation, it is preferable for the hydrostatic internal pressure of the cable to be at or slightly in excess 20 of atmospheric pressure at all times, so that there will be no entrance of air into the cable, in case there should be a leak in the outer sheath, or when the cable ends are opened, as. for example, Tor splicing. For this purpose the hollow tube or tubes 25 are filled with a predetermined amount oi' liquid or gas. When a liquid filler is used, an expansion reservoir is connected to each hollow tube or group of tubes. Fig. 5 illustrates a spring-loaded bellows type of closed reservoir R connected to a 33 pipe I0, the latter being connected to the tube or tubes I within the cable. v

As the temperature ofthe diiierent parts of the cable length changes and there is a difference in the rate oi' expansion oi' those parts, with 35 a relatively 'inelastic outer sheath there is a change in the hydrostatic pressure on the impregnating compound or oil and consequently on the walls of the hollow tubes. YWhen the external pressure on the walls of the hollow tubes is great- 40 er than the internal pressure, the walls will move inwardly, thus reducing the area cross section of the hollow tubes. Conversely, when the external pressure on the walls of the hollow tubes is less than the internal pressure, the walls will move 45 outwardly, thus increasing the area cross section. The movement oi.' the walls of the hollow tubes will continue until there is substantial equalization of pressure.

With a liquid iiller in the hollow tubes at least 50 one expansion tank such as shown in Fig. 5 is mounted on the cable reel and is connected to each hollow tube or to a group of tubes, in the cable length on the reel. Also, with a gaseous nller i'or the hollow tubes, an expansion tank 55 may be utilized, but is unnecessary under normal conditions because a gas is itself expansible. For example, the hollow tubes may open to the outside air, or they may be sealed at the endsand in the latter case the gas will be compressed to 5 a smaller volume by a decrease of cross section of the hollow tubes, and will expand to a greater volume by an increase of cross section, with respectively inverse changes in pressure. With such expansion tanks or openings to the outside .5 air, part of the iiuid in the hollow tubes will pass lengthwise of the cable length (with or without substantial compression in the case oi gaseous fillers) to and from the reservoirs (or alternatively to openings' to the outside air) as the pressure 70 within the cable is greater or less in the reservoirs or at the openings to the outside air.

After the cable lengths have been installed, the hollow tubes or tapes may be connected in various Ways, (see Figs. 8 to 13). 75

accanita tion with the separated tubes of Fig. 8.

A system of hollow tubes, connections B and reservoirs D is shown in Fig. l2. Fig. 13 shows similar reservoirs D used on non-connecting hollow tube lengths.

The description of Figs. 8 to i3 is given by way o clarification of the application ci' the tubes l to the cable.

It is to be understood that the reservoirs may be closed or open as the installation and/or operating conditions require, and that with gaseous fluids the reservoirs of Figs. 9, li, l2 and i3 may be omitted and the connections from the tubes to the outside of the cables either may be closed or may be left open to atmosphere through properly guarded openings. Furthermore, the hollow tubes 4 may be separated at points within a given section of cable S. In this case circulation of uid may not be had unless internal return connections are made but the pressure changing methods herein described may be used without return connections.

Either during the construction of the cable ,splices or preferably after their completion, by

the application of pressure the hollow tubes may be utilized to detect the presence of leaks in the outer sheath and/or to adjust or season the cable prior to placing it in operation. Means and methods corresponding to those described in Fig. 4 are utilized for these purposes but modied as shown in Figs. 6 and '7, and described hereinafter.

By the above used terms adjusting or seasoning is meant the process of introducing liquid or gaseous filler into the hollow tubes within the cable so as to compensate for sheath stretching prior thereto and/or to purposely stretch the sheath and/or to equalize the distribution of compound throughout the cross section and length of the cable, and/or to minimize the void content of the cable. Particularly in highvoltage cables it may be desirable to season the cable before its rated voltage is applied, in order to assure that the void content has been minimized and that the compound distribution is equalized. After adjusting or seasoning, and prior to placing in operation, the predetermined pressure-volume-temperature operating characteristics are established by the quantity of liquid or gas filler in or introduced into the tubes.

The application of pressure to the tube ends, utilizing either gas or liquid as the filler for the tubes, will increase the area of cross section of the tubes and consequently exert pressure on the impregnating compound or oil, thus causing it to flow into areas or sections of the cable which were at lower pressure and lling the void spaces that may have formed there. The pressure may be carried to values above that predetermined for regular operation and even to a value which will stretch the lead sheath slightly in4 order to assure the greatest minimization of void space and/or to expand the hollow tubes from the area of cross section selected for manufacturing convenience to a greater area required for the proper operation of the cable. During the seasoning process there may also be a release of pressure and iurther applications and releases of pressure, to assure the emcacy of the seasonun g ing process.

During the seasoning process, circulation or passage through the hollow tubes oi heated gas or liquid may also be of advantage, particularly under certain conditions; for example, if the im u pregnating compound is viscous or is materially thickened by low temperature. Heated air or oil, for example at or near the maximum operating temperature ci the cable may be passed through the tubes and produce expansion and is mobility of the cable parts suciently close to .conditions under operation to effectually season the cable more rapidly than without heat under certain conditions.

Such applications of pressure and/or heat during the seasoning process may be made to each cable length separately, or to several cable lengths simultaneously, the choice depending upon particular conditions and convenience. For example, certain electrical tests may be required at predetermined temperature and pressure conditions. After the application of pressure and/or heat, the ends of the hollow tubes, if not left open to the outside air, are closed and/or sealed, or connected to reservoirs or expansion tanks, under predetermined pressure-temperature-volume conditions.

Provisions are preferably made so that connections to the hollow tube ends can be made conveniently from time to time after the cable is in operation in order to determine the extent and nature of changes in pressure and fluid volume which may have taken place, and make the necessary adjustments thereto.

In. case it is desired to cool the cable internally, passage cr circulation of the gaseous or liquid filler through the hollow tubes may be employed. In such case, the area cross section and number of the tubes will be determined, among other things, by the character of the cooling 45.

example by throttling by eiecting reduced areas at the discharge openings, or by recirculating through a closed system (preferably utilizing the hollow tubes for the return path) including radiators or cooling coils for cooling the medium.

Fig. 6 illustrates a length or lengths of cable 40, 40, installed and connected to adjacent lengths 4| and 42 by splices 43 and 44 respectively. The continuous or connected xpansible tube 4 in cable length or lengths 40 is connected 60 at the ends through valve fittings I3 and 26 to a system of piping and valves with pressure gauge, pressure pump, and circulating pump, similar to that of Fig. 4. The tube ends from cable lengths 4I and 42 are indicated by numeral v65 45. By this system, each length, or group of associated lengths of cable, can be tested and seasoned after installation, with control of pressure, and if desired the circulation of heated or cooled medium through the tubes.

Fig. '7 illustrates an arrangement similar to Fig. 6 in which the cable contains two tubes 4, and one of them replaces the long tube I0 between fittings 20 and i3 of Fig. 6.

After tests and seasoning, the apparatus .of 75 Figs. 6 or '1, external to the cable. is disconnected and the tube ends are sealed up or connected to reservoirs such as shown in Figs. 8 to 14 with the predetermined amounts of liquid or gas contained therein, or may be left open to atmosphere through properly guarded openings. In case it is desired to cool the cable during operation, the circulating pump 22 will be retained to force the cooling medium through the tubes l, and the tank 30, or its equivalent, with cooling means will be retained in case the cooling medium is to be recirculated.

It is to be understood that certain classes of liquid within the tape are more desirable than others, depending upon particular circumstances.

From the above it will be seen that there is provided a method of adjusting or seasoning cable before comercial operation thereof, or after one or more commercial operations and 'before subsequent ones, said adjustment being made by means of the introduction of optimum pressure and temperature conditions into the expansible tubing in the cable, whereby the relationship between cable parts when they are subsequently in use is substantially at the optimum relationship desired.

In view of the above, it will be seen that th several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in carrying out the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. The method of seasoning cable throughout a predeterminedlength before a subsequent operation thereof, the cable being characterized by an assembly of at least one expansible tube having an outlet and conductors and ller within a sheath, comprising attaching forcing means to said outlet, supplying fluid to the forcing means, forcing said uid into the expansible tube, and maintaining the pressure in the tube at such value that an optimum relationship between the parts ofthe cable assembly exists during subsequent operation of the cable.

2. The method of seasoning cable throughout a predetermined length before a subsequent operation thereof, the cable being characterized by an assembly of at least one expansible tube having an outlet and conductors and filler within a sheath, comprising attaching-forcing means to one end of said expan'sible tube, supplying fluid to the forcing means forcing said iiuid into the expansible tube, maintaining the pressure in the tube at such value that an optimum relationship between the parts of the cable assembly exists during subsequent operation of the cable, and returning the fluid to said forcing means from said outlet.

3. The method of seasoning cable throughout a predetermined length before a subsequent operation thereof, the cable being characterized by an assembly of at least one expansible tube having yan outlet and conductors and filler within a sheath, comprising attaching forcing means to said outlet, supplying uid to the forcing means, forcing said fluid into the expansible tube, maintaining the pressure in the tube at such value that g an optimum relationship between the parts of the cable assembly exists during subsequent operation of the cable, and controlling the temperature of the fluid.

4. 'I'he method of seasoning cable throughout 10 a predetermined length before a subsequent operation thereof, the cable being characterized by an assembly-of at least one expansible tube having an outlet and conductors and filler within a sheath, comprising attaching forcing means to 15 one end of said expansible tube, supplying uid to the forcing means, forcing said fluid through the expansible tube, maintaining the pressure in the tube at such value thatan optimum relation2 ship between the parts of the cable assembly a0 existsduring subsequent operation of the cable, returning the fluid to said forcing means, whereby a circulating system is effected predeterminately, controlling the temperature of the uid in said circulating system, and throttling the cir- 2l culating system for controlling said pressure.

5. The method of seasoning cable throughout a predetermined length before a subsequent operation thereof, the cable being characterized by an assembly of at least one expansible tube so having an outlet and conductors and illler within a sheath, comprising attaching forcing means to one end of said expansible tube, supplying iluid to the forcing means, forcing said fluid through the expansible tube, maintaining the pressure in Il the tube at such value that an optmum relationship between the parts of the cable assembly exists during subsequent operation of the cable, returning the fluid to said forcing means, throttling the circulating system for controlling said 40 pressure, and controlling the temperature of the huid in the circulating system.

6. The method of seasoning cable having an impermeable, expansible tube therein which is in a state other than that assumed during operation, the seasoning being effected throughout a predetermined length of the cable before a subsequent operation thereof, comprising attaching forcing means to one end of said expansible tube, supplying fluid to the forcing means, and vary- 5o ing the pressure applied to the tube outside of the range of the pressures which will occur in operation, in order to effect an adjustment of thel cable parts.

'1. The method of seasoning cable having an 55 impermeable. expansible tube therein which is in a state other than that assumed during operation, the seasoning being effected throughout a predetermined length of the cable before a subsequent operation thereof, comprising attacho0 ing forcing means to one end of said expansible tube, supplying fluid to the forcing means, varying the pressure applied to the tube outside of the range of the pressures which will occur in operation, in order to effect an adjustment, and e5 predeterminately controlling the temperature of the fluid under pressure.

PHILlP H. CHASE.

CERTIFICATE OF CORRECTION.

Patent No. 2,024,144. I December 17, 1935.

It is hereby certified that error appears in the printed specification `of the above numbered patent requiring correction as follows: Page 4, second Column, line 23, claim 4, .after the word "effected" insert a comme.; and line 24, same claim, after the syllable "ly" strike out the comma; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office. l

Signed and sealed `Jthis 24th day of August, A. D. 1937.

Leslie Frezer (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

lement Ne. 2,024,144. Deeember 1'7, 1955.

It is hereby certified that error appears in the printed specification `of the above numbered patent requiring correction as follows-z Page 4, second Column, line 23, claim 4, .after the word "effected" insert e, comme.; and line 24, same claim, after the syllable "ly" strike out the comme.; and that thev 4said Letters Patent should be read with Athese corrections therein v that the same may conform to the record of the Case in the Patent Office.

Signed and sealed Athis 24th day of August, A. D. 193'?.`

Leslie Frazer (Seal) i Acting Commissioner of Patents. 

